A security matrix layer between a first and second conductive shorting layers are located within a printed circuit board (PCB) that carries out cryptographic data handling functions. The security matrix layer includes at least two microcapsules each containing one or more reactants. When the security matrix layer is accessed, drilled, or otherwise damaged, the microcapsules rupture and the reactants react to form at least an electrically conductive material. The electrically conductive material contacts and shorts the first and second conductive shorting layers. A monitoring device that monitors whether the first and second conductive shorting layers have shorted detects the short and passes a tamper signal that is received by one or more computer system devices to respond to the unauthorized physical access attempt.